Method and a support arrangement in a roller vehicle to be steered by a roller mat

ABSTRACT

A method and a support arrangement to steer a roller vehicle by a roller mat, which vehicle has an essentially rigid body part supporting the frame and the power engine with transmission means thereof to transmit power to a curved form turnable roller mat, whereby one side of the roller mat is shortened and the other side thereof is correspondingly lengthened. According to the invention, when the roller mat is being turned to a curved form the vehicle is tilted and its center of gravity is transferred to the side of the tilt in regard to the longitudinal axis of the vehicle. The support arrangement extends essentially the whole length of the body part, is suspended to the body part and comprises a separate, twistable, i.e. bendable or foldable, auxiliary body part supported to the support arrangement at two points on the center line of the vehicle, to which body the roller wheel assembly of the roller mat has been suspended nontransferably in regard to the auxiliary body, and which body is provided with means connected to the steering devices of the vehicle to twist the auxiliary body and thus to steer the vehicle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for steering a roller vehicle by aroller mat and a support arrangement in compliance with a roller vehicleto be steered by a roller mat.

More particularly, the invention relates to a method to steer a rollervehicle by a roller mat, in which the vehicle has an essentially rigidbody part for supporting the frame and a power engine 2 withtransmission means 3 to transmit power to the roller mat which is atleast partially curved to form a turnable roller mat 4, such that oneside of the roller mat is shortened and the other side thereof iscorrespondingly lengthened. The support arrangement to steer the vehicleto a curved form includes the turnable roller mat 4, and the rigid bodypart 1 supports the power engine 2 above and the transmission means 3transmits a driving force directly to the outer periphery of the rollermat 4 adapted around a turnable roller wheel assembly 6, 7 under thebody part 1.

In before-known roller-steered vehicles it has been used twoindividually driven roller mats, whereby by changing their rotationaldirection or speed the steering of the vehicle is accomplished. Theweakness in this arrangement consists of, however, the need of twoseparate steering systems and the complexity and susceptibility todamages of the steering system caused by it.

To eliminate such disadvantages connected with the traditional steeringsystem. There is known a steering system and device for itsimplementation according to the Finnish Patent No. 46708. By theprinciple presented in this patent the vehicle is provided only by oneroller mat arranged around, the front and rear end roller assemblies,one of which is driven by a proper transmission gear of a power engine,and which are turned essentially equally by partial turns and minimumturning radius. In this case the roller mat is forced to a curvedposition effecting the turning. Especially concerning the directionalstability this kind of a steering system is not, however, satisfactory.Particularly to improve the directional stability there is proposed inthe Finnish Patent No. 51922 a better steering system and a device torealize it. The principle of this patent is mainly characterized in thatthe portion of the roller mat on the side of the vehicle's front endwith its end roller assembly is turned by essentially greater turningradii than the minimum turning radius of the vehicle with a higherangular velocity than the rear portion of the roller mat with its rollerassembly and simultaneously the rear end roller assembly and the rearend of the roller mat are forced to function automatically without anyadjustable steering devices.

Both above-mentioned patents with respect to a curved position turnableroller mats have the disadvantage, that the roller mat does not remainover the turning rollers. A solution to this problem has therefore beenattempted to be solved by making on the center line of the roller mat,to the inner periphery of the mat, a projection profiled as a dovetail,to the web of which are supported on both sides a pair of rollersconnected to the steering levers to turn in a way corresponding to theturning of the end roller assembly in order to prevent that the rollermat, influenced by great lateral forces resisting the turning andapplied by the base to the roller mat, would not slide off over the endroller assembly, which would, if happened, make the vehicle completelyunfit for driving and steering. In practical test drives a disadvantagehas anyhow been observed, that the projection formed as a dovetailcannot alone reliably prevent displacement of the roller mat, whichdisadvantage is yet emphasized in curve driving, when it is strived totilt the vehicle to the side of the inner curve, and also in hilldriving, when it is necessary to steer the vehicle obliquely because offor example a natural obstacle or steepness of the hill. Thebefore-known vehicle provided with a roller mat turning as a curveshould therefore be driven by a particular driving style, whereby oneshould always try to keep the vehicle, if possible, in constant positionregarding the surface of the terrain, which can be done, when the drivertransfers his own center of gravity to different locations in thevehicle without tilting the vehicle.

One purpose of the present invention is to eliminate the aforementioneddisadvantages and weaknesses connected with the traditional roller matsteering, and on the other hand to provide a new method and device forsteering of a roller device by a roller mat, so that the steering of theroller device would as accurately as possible resemble the steeringprinciple of a motorcycle.

These purposes has been achieved by the method and arrangement mentionedin the introduction, the characteristic features of which have beenpresented in the enclosed claims.

SUMMARY OF THE INVENTION

According to the invention a device having an essentially rigid bodypart, which supports the frame and the power engine with transmissiongear for power transmission to the roller mat turnable to a curve formto drive the vehicle, and to which device has been supported andsuspended and essentially to its whole length extending bendable orjointably foldable support arrangement, a so-called auxiliary bodycarrying the roller mat, which supports the roller wheel assembly, issteered by tilting and thus by transfer of the center of gravity so,that the roller mat is displaced by bending the support arrangement fromthe direct driving position, in which each side of the roller mat isessentially at the same distance from the body part, to the curvedriving position, in which one side of the roller mat is at leastpartially closer to the body part than the other side thereof, wherebyat the same time as the support arrangement is being bended to displacethe roller mat to the curve driving position, the roller mat itselfbecomes shorter, as is generally known, at its one side and longer atits other side and the body part gets tilted, so that the center ofgravity of the vehicle transfers in regard to the longitudinal centerline to the side of the tilt.

According to an advantageous embodiment of the invention the auxiliarybody consists of rods made of spring steel, which have an inclinationwhen displaced from their balance position to return to their balanceposition, so that the advantage of the automatical return of steeringcan be gained. This effect is enhanced by the fact, that the roller matis prestressed, so that also it has an inclination to return to itsbalance position, i.e. direct driving position, whereby also theauxiliary body formed by rodlike elements, the parts of which body hasbeen made foldable by ball joints, has an inclination to return to itsbalance position or ensure the automatic return of the steering.

One of the main advantages of the invention is, that the curve drivingin terrain, as on roads, is easy and can mainly be compared with themotorcycle driving, and due to the tilting vehicle the driving isreliable and directionally stable even with great speeds and smallturning radii. Because in curve driving or oblique hill driving,according to the most advantageous embodiment of the invention, only theedge zone of the roller mat can be held against the base, the lateralfrictional force resisting the turning and applied by the base to theroller mat is continuously small, wherefore the roller mat even in sharpturns or oblique hill driving does not try to be displaced, so that withthe steering roller vehicle according to the invention can, even withthe load of several persons, also long uninhabited roadless journeys inthe wilderness be reliably driven.

One advantage connected with the invention is still, that no forces areapplied to the roller mat bending it forcibly to a curved form, but thatby bending or folding the support arrangement, i.e. the auxiliary body,and due to the tilting of the vehicle because of it and the shorteningof one side of the roller mat and lengthening of the other side thereofthe roller mat is twisted and placed in a curved position, whereby thecurve or hill drive by the tilting vehicle becomes possible.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be decribed in detail in the following using some ofits advantageous embodiments as examples with reference to theaccompanying drawing, in which FIG. 1 shows a schematic side view of theroller vehicle; FIG. 2 shows the roller vehicle as in FIG. 1 providedwith a support arrangement according to an advantageous embodiment ofthe invention as seen from above with the body part and upper part ofthe roller mat removed and without bending means for the supportarrangement; FIG. 3 shows an enlarged and more detailed sectional viewtaken along the line III . . . III of FIG. 2; and FIG. 4 shows theroller vehicle provided with a support arrangement and bending meansthereof according to another advantageous embodiment of the inventionwith the body part and the upper part of the roller mat removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The vehicle steered by the roller mat comprises:

a rigid body part 1 supporting a power engine 2 above and the powertransmission means 3 connected with it to transmit the driving force tothe roller mat 4,

a separate support arrangement 5, 5' suspended from the body part 1 andsupported to it at two points on the center line of the vehicle, thissupport arrangement being twistable, i.e. bendable or jointablyfoldable, and called in the following as the auxiliary body, to whichhave been suspended the roller wheel assembly 6, 7 of the roller mat 4,and

means 8, 9 connected to the steering equipment of the vehicle to bendthe auxiliary body 5, 5' and thus to steer the vehicle.

The rigid body part 1 is preferably composed of two longitudinal mainbeams 10 and transversal frame beams 11 or a plate uniting them, whichbeams have advantageously been connected to each other by welding toform the mentioned rigid body part 1. The purpose of the body part 1 isto support above it the vehicle frame (not shown) and power engine 2,e.g. a combustion engine, power transmission means 3, e.g. atransmission belt 30, chain etc. and a toothed roller 31 to transmit thedriving force to the outer periphery of the roller mat 4.

To transmit the power to the roller mat 4, its outer periphery isprovided with a transverse configuration suitable for the toothing ofthe toothed roller 31. Advantageously this configuration can be realizedso, that the roller mat consists of in regard to the longitudinal axisof the vehicle transverse small pipe pieces and narrow portionsconnecting these pipe pieces together, whereby the small pipe piecesyielding in the longitudinal direction of the vehicle make thestretching of the roller mat possible. It is further advantageous thatin the roller mat has been formed a channel, to which has been fitted acontinuous, prestressed and at several points in regard to the rollermat non-transferably locked steel wire, which together with the yieldingproperty of the small pipe pieces achieves the shortening of the rollermat. Because the roller mat 4 is bendable to a curved form, it isadvantageous, that the toothing of the toothed roller 31 consists ofindividual teeth, the working surface of which has been formed as acycloid, so that between the configuration of the roller mat 4 and thetoothing of the toothed roller 31 no transverse sliding movement takesplace, which would chafe the roller mat 4, especially when the toothedroller 31 is located so, that it matches the support point in the bodypart of the auxiliary body 5, 5'.

To ensure that the roller mat between the body part 1 and the auxiliarybody 5, 5' would extend symmetrically in regard to its longitudinal axisand straightly to the driving toothed roller 31, the body part 1 isprovided with a slide guide 12 and flexibly supported impellers 13supported to a center ridge 41, which is placed on the inner peripheryof the roller mat 4 symmetrically to the longitudinal axis thereof.

The auxiliary body 5 according to the the first advantageous embodimentof the invention and being best conceivable by FIG. 2 is composed of ajointed lattice 5 consisting of at least three, advantageously four, asin FIG. 2, or five frame parts made of rodlike elements, which parts toenable the twisting of the auxiliary body 5 have been coupled togetheron the longitudinal center line of the vehicle by ball joints 51,whereby the frame parts formed by rodlike elements 55, which to maximizethe structural strength and at the same time the lightness thereof aremade of spring steel pipes or billets, can freely turn to each directionaround the joint point. As shown in FIG. 2, the elements 55 directedoutwards from the ball joints 51 have been adapted to extend obliquelytowards the vehicle sides, so that they leave between them a bendingreserve enabling to bend the auxiliary body 5 to a folded position,which reserve depending on the selected number of the frame parts can bebetween 5° . . . 40°. As further indicated in FIG. 2, the auxiliary body5 extends essentially to the whole length of the roller vehicle, and toone of its end parts has been mounted by bearing brackets 15 the frontend roller wheels 6 and to the other end part the rear end roller wheels6, around which wheels the roller mat is rotating. In order that thebody part 1 and the auxiliary body 5 would maintain their mutualposition, two of the ball joints 51 in the auxiliary body 5 have beensupported non-transferably to the body part 1. To ensure the fixedposition of the auxiliary body 5, the ball joints 51 connected to itsend frame parts, i.e. the ball points nearest to the edge, can besupported to the transverse frame beams 11 of the body part 1.

As shown in FIGS. 2 and 3, the auxiliary body 5 has been suspended tothe body part 1 by several parallelly spaced support bars 52 transverseto the longitudinal axis of the vehicle, the ends of which are directedslantingly downwards from the body part 1. In the preferred embodimentof the invention each support bar has been made of spring steel andformed essentially as a circle segment, moreover to maintain thetransverse position of the support bar 52 each bar 52 has been supportedat three points to the body part 1. In the preferred embodiment thetopmost, i.e. center part of the curve of the support bar 52 has beenrigidly attached, f.ex. by a weld or bolt joint, to the transverse framebeam 11, and the ends thereof by properly dimensioned spacers 56 to thelongitudinal main beams 10.

As is most clearly visible in FIGS. 1 and 3, the intermediate rollerwheels 7 between the end roller wheels 6, supporting the portion of theroller mat 4 against the base between the front and rear end rollerwheels 6, have been rigidly suspended, preferably by torsion arms 70, tothe rodlike elements 55 of the auxiliary body 5. In this way theadvantage is gained, that the intermediate roller wheels 7 can beeffectively moved in vertical direction, whereby the roller wheels 6support all the time the roller mat 4 regardless the unevenness of thebase, and simultaneously a great torsional strength is attained againstlateral bending.

As already stated before, the transverse support bars 52 have beenformed as a circle segment. In this case it is advantageous, that theend of the support bar 52 is placed 2 . . . 10 cm, preferably about 5cm, lower than the middle part of the support bar 52. The auxiliary body5 has been suspended to each support bar 52 by a thrust bearing 53, asshown in FIG. 3, so that when the auxiliary body is being twisted, itcan move laterally on the support bearings 53 along the transversesupport bar 52. Now the auxiliary body 5 is bent to a folded positionand it tilts in regard to the vehicle body part 1 forcing thus theroller wheels on the other side of the roller mat 4 closer to the bodypart and the roller wheels on the opposite side correspondingly fartheraway from the body part, whereby the roller mat 4 is displaced from thedirect driving position to the curve driving position, i.e. curved andan oblique position regarding the vehicle body part, at the same timewhen the center of gravity of the vehicle transfers to the side of thetilt, i.e. to the side in regard to the longitudinal axis of thevehicle, where the roller mat 4 is closer to the body part 1. The formof the support bars 52 determines thus the tilting grade and velocity ofthe vehicle. Regarding the mentioned tilting grade and velocity as wellas driving comfort of the vehicle it is advantageous, that in additionto flexible support bars 52 the spacers 56 supporting their ends aremade of spring means, f.ex. coil springs, or as in FIG. 3 oftelescopically moving pressure springs. Further on it is advantageousespecially in order to set the tilting grade or velocity, i.e. to changethe curvature of the support bar 52, that the length and supporting ofthe spring means 56 in the longitudinal main beam 10 is adjustable. Inthe embodiment in FIG. 3 this has been achieved so, that the fasteningof the other end of the telescope spring 56 acting as a spacer issettable, whereby a sleeve provided with inner threading serves as itssupporting piece 57 in the mean beam 10. By turning the other half ofthe telescope spring in the sleeve, both the position of the springmeans 56 in regard to the body part 1 and the curvature of the supportbar 52 can be changed.

In FIG. 4 has been shown another advantageous embodiment to realize thetwistable auxiliary body 5'. The auxiliary body 5' according to thisother embodiment is as before supported at two points to the rigid bodypart 1 of the vehicle to maintain the mutual adaptation of the auxiliarybody and the body part, and suspended by transverse downwards curvingsupport bars 52 to the vehicle body part 1. The auxiliary body 5'supports as before by the bearing brackets 15 thereof both the front andrear end roller wheels 6 of the vehicle and advantageously by thetorsion arms 60 flexibly suspended intermediate roller wheels 7.

As indicated in FIG. 4, the auxiliary body comprises instead of thejointed arrangement two elongate elements 5' extending essentially alongthe whole vehicle length and being formed to maximize the structurallightness and strength by pipes made of spring steel, so that theseflexible pipes make the bending and twisting of the auxiliary body 5'possible.

According to a preferred embodiment of the invention the auxiliary bodyis twisted to enable the curve driving so, that the corners on the sideof the inner curve of the auxiliary body are forced to transfer towardseach other and the corners on the side of the outer curve are forced totransfer from each other, whereby the jointed auxiliary body 5 accordingto the first embodiment of the invention is folded and tilts, so thatthis tilting corresponds to the curvature of the transverse supportrods, and whereby the auxiliary body 5' according to the secondembodiment of the invention is twisted, so that this twistingcorresponds to curvature of the transverse support bars.

In FIG. 4, there has been shown the means suitable for twisting of boththe auxiliary body 5 according to the first embodiment of the inventionand the auxiliary body 5' according to the second embodiment of theinvention. As can be observed in FIG. 4, the auxiliary body 5, 5'includes:

a torsional element 8 intended for connection to the handwheel bysuitable intermediate rods (not shown), f.ex. a circular or flat plate,which is at the center point thereof mounted in bearings to the bodypart 1, preferably to the transverse frame beam 22, to turn to eitherdirection around its mounting point, and

four pieces of intermediate arms 9, each of which has been axled to theaforementioned torsional element 8 at a distance from its mountingpoint, and at the other end thereof to the auxiliary body 5, 5'. Axlingof the other ends of the intermediate arms 9 can be in a most simple waybe realized by utilizing bearing brackets 15 near the vehicle corners,intended for the suspension of axles 60 of the front and rear end rollerwheels 6 of the vehicle, to which brackets can be mounted suitablevertical spindles for this purpose.

That, when the torsional element 8 is being turned, the auxiliary body5, 5' would bend to the desired direction, or that the corners of theauxiliary body on the side of the inner curve would come closer to eachother, it must be observed in the axling of the intermediate arms, thatthe ends of the intermediate arms 9 directed to one side of the vehicleand axled to the torsional element 8 are twisted to opposite directionsin regard to the longitudinal line through the mounting point of thetorsional element 8, when the torsional element 8 is being turned. Thiscan be carried out by for instance the arrangement according to FIG. 4,in which the intermediate arms 9 axled crosswise to the corners of theauxiliary body 5' have been axled to the same point in the torsionalelement 8. Alternatively can the intermediate arms, axled to the frontcorners of the support arrangement 5, 5', be axled to one point in thetorsional element 8 and correspondingly the intermediate arms axled tothe back corners of the support arrangement 5, 5' can be axled toanother point in the torsional element 8.

It must be stated concerning the auxiliary body according to the secondadvantageous embodiment of the invention, that the elongate elements 5'are parallel and spaced from each other, so that when the auxiliary body5' is being twisted a tensile stress is developed in one elongateelement striving to stretch this element, and a compressive stress inthe other element striving to bend this elongate element to a curvedform. To compensate the tension caused by the tensile stress eachelongate element 5' consists of telescopically within each other movingspring steel pipes, the total length of which is in its minimum when thesupport arrangement is not bent. Because the telescope pipe has theaforementioned minimum length, the telescope pipe on the side of theinner curve is turned to a curved form when the auxiliary body is beingtwisted because of the approaching of the mounting points thereof, whichadditionally generates a counterforce corresponding to the bend andstriving to compensate the twisting, which force in this secondadvantageous embodiment of the invention makes the automatic steeringoperational again.

In a preferable embodiment of the invention the peripheral length of theroller mat 4 becomes smaller towards the edges thereof, whereby theedges of the roller mat are apart from the base in the direct drivingposition and only the middle part of the roller mat is supported to thebase. In this embodiment the roller mat itself rotates centripetallyaround the roller assembly and does not strive to be displaced fromabove the roller wheel assembly 6, 7. As can be seen in FIG. 3, theroller wheels have been dimensioned and supported to support the rollermat form, which is laterally outward slanting. To ensure the stationaryposition of the roller mat, the height of the center ridge 41 extendingbetween the roller wheels 6, 7 has been dimensioned to correspond atleast half of the diameter of the innermost intermediate roller wheels6, so that the roller wheels cannot inadvertently "climb" over thecenter ridge, which, if happened, could lead to the displacement of theroller mat.

The invention has been described above only by some of its advantageousembodiments. This does not, of course, have any restrictive nature forthe invention and as it is clear to those skilled in the art, there arevarious modifications and alternative arrangements possible within thescope of appended claims. This concerns particularly the form andsuspension of the transverse bar and also the structure and equipment ofthe auxiliary body itself, for example the use of pneumatics orhydraulics to twist and/or bend the auxiliary body and thus to tilt theroller mat and the vehicle body in regard to each other as well as tobend the roller mat to a curved form.

I claim:
 1. A support arrangement in a roller vehicle for steering thereof, including:a turnover roller mat 4; a rigid body part 1 for supporting a power engine 2 and transmission means 3 for transmitting a driving force directly to an outer periphery of said roller mat 4 movable around a turnable wheel assembly 6, 7 under said rigid body part 1; a support arrangement 5 extending the whole length of said body part 1 and suspended therefrom, said support arrangement including a separate, twistable auxiliary body 5, 5' supported by said body part 1 at two points on a center line of said vehicle; said roller wheel assembly 6, 7 being suspended by said auxiliary body 5, 5'; said auxiliary body being provided with means 8, 9 connected to steering means for said vehicle for twisting said auxiliary body 5, 5' for steering said vehicle; said auxiliary body including two flexible, telescopically lengthening rod means, the length of said rod means being at a minimum extent when said auxiliary body is in a unfolded balance state; said auxiliary body 5, 5' being connected to said body part 1 by several parallel and spaced downwardly directed support rods 52 transverse to a longitudinal axis of said vehicle passing through a center of gravity of said vehicle defining a longitudinal center line thereof, each of said rods being supported to maintain the transverse position thereof at three points to the body part 1; said auxiliary body 5, 5' being suspended to each support rod 52 by at least two thrust bearings 53, so that when said auxiliary body 5' is twisted it can move on said thrust bearings 53 along said transverse support rods 52, whereby on one side of said roller mat 4, the distance between said roller wheels 6, 7 and said body part 1 is shorter and on the other side of said roller mat 4 the distance between the roller wheels 6, 7 and the body part 1 becomes correspondingly longer, so that the roller mat 4 is displaced from a direct driving position to a curved driving position, at the same time when the center of gravity of the vehicle transfers from a side towards which said vehicle tilts on one side of the longitudinal center line of the vehicle to a side on the other side of the longitudinal center line of said vehicle, whereat said roller mat 4 is closer to said body part
 1. 2. The support arrangement according to claim 1, wherein said auxiliary body 5 comprises:a jointed lattice 5 having at least three frame parts made of rod-like elements 55, said frame parts including ball joints 51 for coupling said frame parts together on the longitudinal center line of the vehicle, two of said ball joints being connected to frame parts nearest an edge of said vehicle; and elements directed outwardly form said ball joints 51 extending obliquely towards sides of said vehicle for providing between them a turning reserve enabling a folding of said auxiliary body
 5. 3. The support arrangement as claimed in claim 1, wherein said transverse support rods 52 are formed as a circle segment, and said support rods have ends placed between 2 and 10 cm lower than a center part of said support rod 52, from which center part said support rod 52 has been supported directly and firmly to the body part 1, and spacers 56 coupled to the ends of said support rods 52 for supporting said body parts.
 4. The support arrangement as claimed in claim 3, wherein said spacers 56 supporting the ends of said support rods 52 comprise spring means 56, and including means for increasing the length of each said spring means
 56. 5. The support arrangement as claimed in claim 4, wherein a means 8, 9 to twist said auxiliary body 5, 5' comprises a torsional element 8, said torsional element including a circular plate mounted at a center point thereof in bearings to said body part 1 allowing turning movement in each direction around said center point, and at least four intermediate arms 9 each arm having two ends, each of said arms at one end thereof being axled to said torsional element 8 at a distance from said center point, and at the other end thereof mounted to said auxiliary body 5, 5' at corners thereof, said auxiliary body having at least four corners.
 6. The support arrangement as claimed in claim 5, wherein said intermediate arms 9 have ends axled to said torsional element 8 and are twisted to opposite directions in regard to the longitudinal line going through the mounting point of the torsional element 8 when said torsional element 8 is being twisted.
 7. The support arrangement as claimed in claim 6, wherein said roller mat 4 has a peripheral length which becomes smaller towards the edges thereof, said roller mat having a base and a center part, said edges of said roller mat 4 being in a direct driving position apart from said base and only said center part of said roller mat being supported to said base, and said roller wheels 6, 7 being dimensioned and suspended flexibly to said auxiliary body 5, 5' to support at least a part of said roller mat
 4. 8. The support arrangement as claimed in claim 1, wherein said roller mat 4 has a peripheral length which decreases towards edges thereof, said roller mat having a base and a center part, said edges of said roller mat 4 being in a direct driving position apart from said base and only said center part of said roller mat being supported to said base, and said roller wheels 6, 7 being dimensioned and suspended flexibly to said auxiliary body 5, 5' to support at least a part of said roller mat
 4. 9. The support arrangement as claimed in claim 2, wherein said transverse support rods 52 are formed as a circle segment, and said support rods have ends placed between 2 and 10 cm lower than the center part of said support rod 52, from which center part said support rod 52 has been supported directly and firmly to the body part 1, and spacers 56 coupled to the ends of said support rods 52 for supporting said body parts.
 10. The support arrangement as claimed in claim 1, wherein a means 8, 9 to twist said auxiliary body 5, 5' comprises a torsional element 8, said torsional element including a flat plate mounted at a center point thereof in bearings to said body part 1 allowing turning movement in each direction around said center point, and at least four intermediate arms 9 each arm having two ends, each of said arms at one end thereof being axled to said torsional element 8 at a distance from said center point, and at the other end thereof mounted to said auxiliary body 5, 5' at corners thereof, said auxiliary body having at least four corners.
 11. The support arrangement as claimed in claim 10, wherein said intermediate arms 9 have ends axled to said torsional element 8 and are twisted in opposite directions relative to a longitudinal line going through the mounting point of the torsional element 8 when said torsional element 8 is being twisted.
 12. The support arrangement as claimed in claim 11, wherein said roller mat 4 has a peripheral length which becomes smaller towards edges thereof, said roller mat having a base and a center part, said edges of said roller mat 4 being in a direct driving position apart from said base and only said center part of said roller mat being supported to said base, and said roller wheels 6, 7 being dimensioned and suspended flexibly to said auxiliary body 5, 5' to support at least a part of said roller mat
 4. 13. The support arrangement as claimed in claim 12, wherein said transverse support rods 52 are formed as a circle segment, and said support rods have ends placed between 2 and 10 cm lower than the center part of said support rod 52, from which center part said support rod 52 has been supported directly and firmly to the body part 1, and spacers 56 coupled to the ends of said support rods 52 for supporting said body parts.
 14. The support arrangement as claimed in claim 1, wherein the support rods 52 have ends, further including spacers 56 supporting the ends of said support rods 52, said spacers comprising springs.
 15. A method to steer a roller vehicle, said vehicle comprising:a turnover roller mat 4 having an outwardly curved center section and two spaced side sections, each side section having two corners; a rigid body part 1 for supporting a power engine 2 and transmission means 3 for transmitting a driving force directly to an outer periphery of said roller mat 4, said roller mat being movable around a turnable wheel assembly 6, 7 located under said rigid body part 1; a support arrangement extending the whole length of said body part 1 and being suspended therefrom, said support arrangement including a separate, twistable auxiliary body 5, 5' supported by said body part 1 at two points along the center line of said vehicle; said auxiliary body 5, 5' being connected to said body part 1 by a plurality of parallel spaced downwardly directed support rods 52 extending transversely to the longitudinal axis of said vehicle and passing through the center of gravity of said vehicle thus defining a longitudinal center line thereof, each of said rods being supported at three points to the body part 1 to maintain the transverse position thereof; the method including the steps of turning the roller mat 4 to a curved position, forming an inner curve on one side section and an outer curve on the other side section for moving the each corner of said roller mat 4 simultaneously on the side section of said inner curve towards each other and said body part 1, and moving the corners on the side section of the outer curve away from each other and away from the body part 1 so as to tilt the vehicle corresponding to the curvature of the transverse support rods 52, wherein the tilt is adjusted by changing the curvature of the transverse support rods.
 16. The method of claim 15, wherein said roller mat has a parabolic curvature. 